5.1 problem 1
5.2 problem 2
5.3 problem 3
5.4 problem 4
5.5 problem 5
5.6 problem 6
5.7 problem 7
5.8 problem 8
5.9 problem 9
5.10 problem 10
5.11 problem 11
5.12 problem 12
5.13 problem 13
5.14 problem 14
5.15 problem 15
5.16 problem 16
5.17 problem 17